check box control in the grid view

Label1.Text = ((CheckBox)GridView1.SelectedRow.Cells[1].Controls[0]).Checked.ToString();

protected void CheckBox_Checked(object sender, EventArgs e)
{
     CheckBox chkbox = (CheckBox)sender;
     GridViewRow r = (GridViewRow)chkbox.NamingContainer;
    if(chkbox.Checked)
      {
             //You can update values by referring (r.FindControl("id of sth control") as SomeTypeControl).PublicProperty
      }
}

foreach(Gridviewrow gvr in Gridview1.Rows)
{
 if(((CheckBox)gvr.FindControl("CheckBox1")).Checked == true)
 {

   int CustomerId = int.parse(gvr.Cells[2].Text);
 }
}

foreach (GridViewRow gvr in showDetails.Rows)
                       {
                           CheckBox chkSelect = gvr.FindControl("chkSelect") as CheckBox;

                           if (chkSelect != null && chkSelect.Checked == true)
                           {
                               if (gvr.Cells[1].Text != "Email Not Valid")
                               {
                                   blObj.importingUserIntoGroup(gvr.Cells[1].Text, user_Id);
                               }
                           }

                       }

foreach(GridViewRow gvr in GridView1.Rows)
{
    // You should have the checkbox in the item template
    if(((CheckBox)gvr.FindControl("CheckBox1")).Checked)
    {
        // Your code goes here.
        // Access yout controls using gvr.FindControl() in case of item templates
        // Use "gvr.Cells[index].Text" in case of grid bound column
    }
}